This invention is generally in the field of devices for the withdrawal and sensing of biological fluids, such as in the analysis of blood glucose levels.
The extraction of analytes through the skin is critical to diabetic patients, who typically must measure blood glucose several times per day in order to optimize insulin treatment and thereby reduce the severe long-term complications of the disease. Currently, diabetics do this by pricking the highly vascularized fingertips with a lancet to perforate the skin, then milking the skin with manual pressure to produce a drop of blood, which is then assayed for glucose using a disposable diagnostic strip and a meter into which the strip fits. This method of glucose measurement has the major disadvantage that it is painful, so diabetics do not like to obtain a glucose measurement as often as is medically indicated. It would therefore be highly useful to be able to obtain a sample of blood, lymph, or interstitial fluid more quickly, using an easier procedure, and relatively noninvasively. It also would be advantageous to be able to repeatedly or continually extract analyte transdermally over a period of time.
Another common technique for withdrawal of bodily fluids, such as for diagnostic purposes, is the use of a needle, such as those used with standard syringes or catheters. While effective for this purpose, needles are invasive and generally cause pain; local damage to the skin at the site of insertion; and bleeding, which can increase the risk of disease transmission. Needle techniques also generally require administration by one trained in its use, and are not preferred for frequent routine use due to the vascular damage caused by repeated punctures. Some proposed alternatives to the needle require the use of (1) lasers or heat to create a hole in the skin, which is inconvenient, expensive, or undesirable for repeated use; (2) electric fields or ultrasound, which also is inconvenient and expensive; or (3) chemical or biological penetration enhancing agents, which can be irritating to the tissue and undesirable for repeated use.
It is therefore an object of the present invention to provide a device for controlled sampling of biological fluids in a minimally-invasive, painless, and convenient manner.
It is another object of the present invention to provide a device for sensing of biological fluids in a minimally-invasive, painless, and convenient manner.